Beans have been a basic food staple of humans for centuries. Traditionally, beans have been dehydrated so as to allow for storage for long periods of time. It has been necessary to dehydrate the beans because fresh hydrated beans suffer from such problems as spoilage and sprouting. In fact, fresh hydrated beans generally have a shelf life of less than a week and, more typically, approximately 3 days. The dehydration process has typically removed most of the water in the bean, with the amount of water generally being reduced from about 50% total moisture in the bean down to about 5% total moisture in the bean. The reduction in water down to 5% total moisture in the bean prevents spoilage in the bean by not leaving a sufficient amount of water available for microbial growth, which includes fungal and bacterial growth. Additionally, beans cannot sprout if there is not sufficient moisture available. Sprouting is undesirable in commercially available beans because consumers will typically refuse to purchase beans that have sprouted in the packaging. Also, sprouts change the flavor of the bean by releasing enzymes which mobilize or change starch to sugar and proteins to amino acids.
While dehydrated beans have desirable storage characteristics, such as eliminating microbial growth and sprouting, they suffer from the inability to be quickly hydrated and made suitable for human consumption within a short period of time. The necessary time required to prepare dehydrated beans for human consumption is a minimum of eight hours for the home cook and two hours for most commercial production operations. Typically, most commercial production operations retort the beans, which involves using pressure to cook the beans. Retorting results in a quicker preparation time; however, retorting or canning the beans imparts disadvantages that will be discussed below. Thus, it is desirable to have a bean that can be stored for long periods of time without spoiling and sprouting, but which can be hydrated and suitable for human consumption within a short amount of time. It would be most preferred to have a bean that is table ready within 10 minutes.
Attempts have been made at producing an intermediate moisture bean that can be prepared for human consumption in a short period of time and can be stored for long periods of time. One prior art method, Staley U.S. Pat. No. 4,510,164 discloses combining beans, water, polyglycol, and propylene glycol in a mixing unit and allowing the glycol and water to diffluse into the beans being treated. This process results in a treated bean that can be stored for a period of time and which can be made ready to eat or table ready in a short amount of time. However, the process suffers from a number of limitations. The resulting bean typically is wrinkled so that it does not have a pleasing visual appearance, which is a problem for beans that are placed in clear packaging. Additionally, the bean is discolored which also detracts from the visual appearance of the bean. Wrinkling and discoloration are problems because an important part of marketing food products is the visual appearance. If a product has a displeasing, non-natural look it is less likely to be purchased by consumers.
When glycols, water, and beans are combined in the same treatment step osmotic competition results. The osmotic competition causes a longer hydration time because glycol will bind water molecules outside the bean which in turn prevents the bean from hydrating as readily. Also, the glycol is bound to the water molecules thereby preventing the glycol molecules from readily passing into the bean. Essentially, the glycol molecules are attracted to water and, as such, will not be attracted to the moisture in the bean. Consequently, the glycol holds the water back from the beans being treated, which then requires a user to increase the temperature and to implement the use of pressure to increase the diffusion of the glycol and water into the beans. Glycol also raises the boiling point of the water so that much higher temperatures must be used to diffuse the glycol into the beans. However, as the temperature is increased, a Maillard browning reaction occurs, as well as caramelization.
A more important problem with the process of combining the beans, water, and glycol in the same step is that the treated beans will have a reduced flavor quality due to inappropriate flavor and caramelization. Caramelization is a reaction between the sugars in the beans that occurs at temperatures greater than 100.degree. C. and causes the sugars to react and form a caramel like or thickened sugar substance. The beans are caramelized as a result of having to mix the bean, water, polyglycol, and propylene glycol mixture at high temperatures of about 100.degree. C. to about 140.degree. C. so that the water and glycols will diffuse into the bean cell structure. If temperatures of greater than 100.degree. C. are not used the glycols and water will not diffuse into the beans. Caramelization is especially undesirable because it alters the flavor, color, and aroma of the treated bean, and causes skin fracturing in the bean. Skin fracturing is undesirable because it causes the skin of the bean to peel and this detracts from the visual appearance of the bean. Additionally, caramelized beans will have a darker color, will smell burnt, and will have a flavor that makes the beans taste as if they have been cooked.
Combining the beans, glycols, and water in the same step also results in Maillard browning which is a process wherein the proteins and simple sugars found in the bean react with one another. When the proteins and simple sugars react with one another they produce a compound that is neither a simple sugar, carbohydrate, or a protein and which reduces the nutritional value of the bean. The Maillard browning reaction reduces the availability of protein in the treated bean so that when a human consumes the bean they receive less available protein than what they would receive from a bean not treated with this process. Maillard browning also creates a hard outer shell on the bean, as the Maillard browning reaction causes cross linking in the outer shell of the bean. Once the shell is cross linked, the shell becomes less penetrable to water molecules and this makes it more difficult for the bean to become rehydrated.
An additional problem resulting from treating a bean in a water and glycol mixture is that the treated bean will have rehydration problems. The treated beans will not hydrate as readily because the process, which uses high temperatures to induce the glycol to diffuse into the bean, will partially cook the beans, which will in turn cook the starches and proteins found in the beans. The cooked starches and proteins will have an altered structure which will prevent some water absorption. Thus, it is further desired to have a process that results in a treated bean that is easily rehydrated, has a full complement of protein, has a pleasing visual appearance, and that does not have an altered flavor. Also, it is desirable to have a treated bean that is not caramelized, nor that has been subject to a Maillard browning reaction. In other words, a bean is desired that has characteristics similar to a fresh untreated bean, such as a smooth skin, natural color, and natural taste as well as breakage characteristics similar to a fresh bean.
Other processes used for producing consumable beans have included canning beans, but canned or retorted beans suffer from the disadvantages of lacking flavor and freshness, because retorting the beans involves cooking the beans. Typically, the retorting will cause the beans to overcook, which results in beans that are mushy and water logged. Most importantly, the retorted beans tend to have a lower nutritional value as a result of reduced protein quality. The flavor is further altered by having the lining of the can influence the flavor of the beans, as the epoxy lining on cans can influence the flavor of the beans. Additionally, canning can be undesirable because the beans cannot be viewed by the consumer and, typically, flavoring is added to the retorted beans which the consumer may not want.
A final known process uses salt and water to lower the water activity of the treated bean. This process does produce a bean that is natural looking and has extended storage capabilities; however, this process suffers from the disadvantage that large amounts of salt must be used. The use of salt is undesirable because of the negative health effects associated with adding too much salt to a person's diet. Not only does salt have negative health consequences, but if not enough salt is added, the water activity is not sufficiently lowered so that the potential for microbial growth readily exists. Thus, it is further desired to have a process that produces a bean that does not incorporate preservatives with harmful short term and long term side effects.